Elon Musk, the billionaire CEO of Tesla and SpaceX, is reportedly facing a criminal probe by the Justice Department into Musk's Aug. 7 tweet about taking Tesla private. The investigation is just the latest piece of bad news for Tesla and Musk, who has faced growing criticism over his recent behavior.

But, at least Musk has Neil deGrasse Tyson on his side. The famed astrophysicist recently had some strong words for Musk's critics.

"Can they leave him alone?" Tyson asked in a recent interview with TMZ , posted on YouTube Sept. 12. Tyson was referring to the criticism that has been heaped upon Musk, the CEO of Tesla and SpaceX, after he was filmed drinking alcohol and smoking marijuana during a podcast interview with comedian Joe Rogan in early September.

"Let the man get high if he wants to get high," Tyson said to TMZ about Musk.

With regard to the regulatory investigation of Musk's tweet, however, the scientist Tyson noted that, as the CEO of a public company, Musk must be held accountable to federal financial laws. "He's got to obey the SEC, clearly … there's an accountability to the public trust," Tyson told TMZ.

Marijuana is legal in California, where Musk was filming the podcast, but critics said the incident was the latest example of erratic behavior from the billionaire. Tesla board members have reportedly expressed concerns in the past about Musk's use of recreational and prescription drugs, according to The New York Times . Now, as CNBC previously reported , Musk may have violated Tesla's business conduct policy by imbibing alcohol and marijuana while representing the company during the podcast.

Meanwhile, Musk has also made negative headlines recently by insulting a British cave diver who helped rescue boys trapped in a Thailand cave, and the CEO is also facing an SEC investigation into his August tweet suggesting he might take Tesla private.

However, Tyson still supports Musk amid the recent wave of criticism of the billionaire. Tyson even compares the Tesla CEO and SpaceX founder to one of America's greatest innovators.

"Count me as Team Elon …" Tyson says in the interview. "He's the only game in town. He's the best thing we've had since Thomas Edison."

Tyson, who is the Frederick P. Rose Director of the Hayden Planetarium at the Rose Center for Earth and Space in New York City, previously defended Musk in a live interview with CNBC . Tyson told CNBC that Musk should be allowed to be himself, arguing that people should "let the man be an individual."

Musk, also CEO and founder of aerospace company SpaceX, announced Monday the first passenger on a private space flight around the moon will be Japanese billionaire fashion magnate Yusaku Maezawa, who is rock musician and art collector as well.

Given Musk's interest in space travel and Tyson's knowledge, TMZ also asked the scientist for his thoughts on whether it's possible (or advisable) to smoke marijuana in space.

"The problem is, in space now many things will kill you. So, if you do anything to alter your understanding of what is reality, that's not in the interest of your health," Tyson told TMZ. "So, if you want to get high in space, lock yourself in your cabin and don't come out. Because you could break stuff... inadvertently."